Ultra High Molecular Weight Poly-Ethylene (UHMWPE) is commonly used in armor applications. Its high strength combined with its elongation properties makes it an ideal material for stopping ballistic threats. Currently there are two common forms of the material which are used in armor applications. “Soft” applications where plies of UHMWPE are layered in conjunction with one another to preserve flexibility, and “hard” applications where the layers of UHMWPE are heated and pressed together to bond the material into a solid.
“Soft” applications are most common in the body armor industry, where flexibility is required in order to preserve comfort. The downside is that the same amount of UHMWPE when bonded together will yield much higher performance (i.e. will stop ballistic threats with much more energy).
The material in its “hard” form is most commonly found in vehicle and installed armor applications. These applications do not require flexibility, so they are able to achieve better performance and lower weight using less material when bonded into a rigid panel. There are some combined applications of soft and hard ballistics for body armor. In this approach the larger area of the body is covered by an un-bonded material. In addition to this “soft material” a hard plate is used over the central portion of the body however the size and coverage of this high performance panel is restricted because of low flexibility. The goal of improved armor material is to have the improved performance of the fully bonded hard panel with the flexibility of the single layers.
UHMWPE fibers are described above because at the current time this fiber has the best tenacity, 24-35 grams per denier, depending on how the fiber is measured. However, there is much work being done to discover or develop even better fibers for the armor applications described above. For example, Arimid fibers are easy to laminate, and PBO (poly p-phenylene-2,6-bezobisoxazole or ZYLON®) and M5®, fibers may yet find greater application in this area.